The present invention relates to internally cooled panels for metallurgical furnaces, and more particularly relates to an improved construction and arrangement for water-cooled panels adapted for use in assembly into fume hoods, ducts or the like, for metallurgical furnaces, such as basic oxygen furnace, electric furnace, converters and the like. This invention relates to and constitutes a modification over the type of panel and fume hood assembly contained in U.S. application Ser. No. 572,403 filed Aug. 15, 1966 to June H. Reighart, now U.S. Pat. No. 3,445,101.
Heretofore, such panels have been employed in sections and/or assembled into fume hoods for transmitting gasses emitted during operation of the furnace to a stack where they are cooled for ultimate disposition so as to avoid the loss of such gasses and to prevent contamination of the atmosphere. The individual panels, or sections, from which the hood may be assembled are water-cooled in order to protect the hood as well as to aid and cool the gasses emitted during the oxygen blow. By reason of the high temperatures and velocities with which the gasses contact the hood, the water-cooled linings of the hood are subject to rapid deterioration and require frequent repair and/or replacement. Moreover, as there is a considerable difference in temperature between the hot and cold sides of the panel, there results a greater expansion of the metal on the hot side. This heat differential causes the panel to buckle or to warp generally in a vertical direction requiring frequent repair and/or replacement. Specifically, the drastic temperature differentials encountered during the oxygen blow initiates internal stresses in the component parts of the panel and/or fume hood assembly which results in a tendency for the parts to pull and/or tear apart, particularly at the weld joints. Accordingly, in addition to the cost of repair and/or replacement of the panel, the loss of production time during the replacement period represents a considerable increase in production costs.
In addition to the foregoing, the panels should be constructed and arranged to provide an optimum uniform longitudinal coolant flow through the panel with minimum cross flow or channeling for maximum heat transfer. More specifically, the panel of the present invention is constructed and arranged to provide a more uniform and controlled flow of coolant through the panel so as to minimize the diffusion type effect, particularly in the manifolds, so as to remove the concentration of stresses at the weak points, such as the weldments, and so as to otherwise avoid hot spots and failures which have heretofore occurred with prior art panels. Manifestly, by this improved arrangement, the life of each panel may be prolonged so as to increase the over-all efficiency of the furnace operation.
In accordance with one aspect of the present invention, the panels are formed so as to reduce welds, both on the inside and outside of the hot face so that a practically seamless face is presented to the fume, while retaining the necessary resistance to movement under hydrostatic pressure. The panels thus formed provide single-pass unidirectional fluid flow which is non-turbulent so as to effectively wash the panel hot face plate. Preferably, the desired spacing between the hot and cold face plates is achieved by plug welds extending axially thereof, insuring equalization of pressure in all fluid passageways with controlled interflow between passageways. The turbulence-free flow thus obtained has marked advantages; the flow pattern takes maximum advantage of natural convection forces in all vertical and inclined panels. The flow resistance is minimal, thus reducing pressure drop through the panel and reducing the possibility of hose, fitting and pipe leaks, extending pump life, and allowing more water to flow through the panels for a given supply pressure. The flow is without eddy-currents and sharp bends which tend to cause bubbling and to precipitate solids in the water. The smooth stream prevents dead spots for contaminants to settle and accumulate. These advantages give extended trouble-free service life to the panels.